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    J250

    OCR GCSE Combined Science Equation Sheet (J250)

    Free OCR GCSE Combined Science equation sheet: open the official OCR (J250) PDF plus all 48 formulas listed by topic, showing which 23 you must memorise.

    48

    Formulas listed

    23

    You must memorise

    25

    Given in the exam

    Official OCR Gateway Physics Equation Sheet (J249)

    Official OCR PDF

    Open on OCR

    Periodic Table

    Given in the Chemistry exams — interactive version

    Open periodic table

    Physics

    26 formulas across 6 topics

    Particles

    Density

    Given in exam
    ρ=mV\rho = \dfrac{m}{V}

    Gas law (constant temperature)

    Given in exam
    pV=constantpV = \text{constant}

    Energy

    Change in thermal energy

    Given in exam
    ΔE=mcΔθ\Delta E = mc\Delta\theta

    Specific latent heat

    Given in exam
    E=mLE = \text{mL}

    Kinetic energy

    Given in exam
    Ek=12mv2E_k = \tfrac{1}{2}mv^2

    Power (work)

    Given in exam
    P=WtP = \dfrac{W}{t}

    Energy stored in a spring

    Given in exam
    E=12kx2E = \tfrac{1}{2}kx^2

    Gravitational potential energy

    Given in exam
    E=mghE = \text{mgh}

    Efficiency

    Given in exam
    efficiency=useful output energyinput energy\text{efficiency} = \dfrac{\text{useful output energy}}{\text{input energy}}

    Motion

    Distance travelled

    Given in exam
    s=vts = \text{vt}

    Acceleration

    Given in exam
    a=v−uta = \dfrac{v - u}{t}

    SUVAT

    Given in exam
    v2−u2=2asv^2 - u^2 = 2\text{as}

    Forces

    Force = mass × acceleration

    Given in exam
    F=maF = \text{ma}

    Work done

    Given in exam
    W=FsW = \text{Fs}

    Hooke's law

    Given in exam
    F=kxF = \text{kx}

    Weight

    Given in exam
    W=mgW = \text{mg}

    Pressure

    Given in exam
    p=FAp = \dfrac{F}{A}

    Moment

    Given in exam
    M=FdM = \text{Fd}

    Electricity

    Charge

    Given in exam
    Q=ItQ = \text{It}

    Potential difference (Ohm's law)

    Given in exam
    V=IRV = \text{IR}

    Energy transferred (charge × pd)

    Given in exam
    E=QVE = \text{QV}

    Electrical power

    Given in exam
    P=VIP = \text{VI}

    Power (I² × R)

    Given in exam
    P=I2RP = I^2 R

    Energy transferred (power × time)

    Given in exam
    E=PtE = \text{Pt}

    Waves

    Wave speed

    Given in exam
    v=fλv = f\lambda

    Time period

    Memorise
    T=1fT = \dfrac{1}{f}

    Not printed on the OCR equation sheet.

    Chemistry

    13 formulas across 7 topics

    Moles & Mass

    Number of moles

    Memorise
    n=massMrn = \dfrac{\text{mass}}{M_r}

    M_r = relative formula mass.

    Mass from moles

    Memorise
    mass=nMr\text{mass} = nM_r

    Avogadro's number

    Memorise
    number of particles=n×6.02×1023\text{number of particles} = n \times 6.02 \times 10^{23}

    Percentage by mass of an element

    Memorise
    % by mass=Ar×number of atomsMr×100\%\text{ by mass} = \dfrac{A_r \times \text{number of atoms}}{M_r} \times 100

    Solutions

    Concentration (g/dm³)

    Memorise
    concentration=massvolume\text{concentration} = \dfrac{\text{mass}}{\text{volume}}

    Volume in dm³ (1 dm³ = 1000 cm³).

    Concentration (mol/dm³)

    Memorise
    concentration=molesvolume\text{concentration} = \dfrac{\text{moles}}{\text{volume}}

    Gases

    Volume of a gas at RTP

    Memorise
    volume=24n\text{volume} = 24n

    RTP: 24 dm³ per mole.

    Yield & Economy

    Percentage yield

    Memorise
    % yield=actual masstheoretical mass×100\%\text{ yield} = \dfrac{\text{actual mass}}{\text{theoretical mass}} \times 100

    Atom economy

    Memorise
    % atom economy=Mr of desired producttotal Mr of products×100\%\text{ atom economy} = \dfrac{M_r\ \text{of desired product}}{\text{total }M_r\ \text{of products}} \times 100

    Energy Changes

    Energy change of a reaction (Higher)

    Memorise
    Q=mcΔTQ = mc\Delta T

    Used in calorimetry experiments.

    Rates

    Mean rate of reaction

    Memorise
    mean rate=quantity of reactant usedtime\text{mean rate} = \dfrac{\text{quantity of reactant used}}{\text{time}}

    Mean rate (product formed)

    Memorise
    mean rate=quantity of product formedtime\text{mean rate} = \dfrac{\text{quantity of product formed}}{\text{time}}

    Electrolysis

    Charge in electrolysis (Higher)

    Memorise
    Q=ItQ = \text{It}

    Biology

    9 formulas across 6 topics

    Cells

    Magnification

    Memorise
    magnification=image sizeactual size\text{magnification} = \dfrac{\text{image size}}{\text{actual size}}

    Real size from image

    Memorise
    actual size=image sizemagnification\text{actual size} = \dfrac{\text{image size}}{\text{magnification}}

    Surface area to volume ratio

    Memorise
    SA:V=surface areavolume\text{SA:V} = \dfrac{\text{surface area}}{\text{volume}}

    Health

    Body Mass Index (BMI)

    Memorise
    BMI=mass (kg)(height in m)2\text{BMI} = \dfrac{\text{mass (kg)}}{(\text{height in m})^2}

    Waist : hip ratio

    Memorise
    ratio=waist circumferencehip circumference\text{ratio} = \dfrac{\text{waist circumference}}{\text{hip circumference}}

    Circulation

    Cardiac output

    Memorise
    cardiac output=stroke volume×heart rate\text{cardiac output} = \text{stroke volume} \times \text{heart rate}

    Transport

    Percentage change in mass (osmosis practical)

    Memorise
    % change=final−initialinitial×100\%\text{ change} = \dfrac{\text{final} - \text{initial}}{\text{initial}} \times 100

    General

    Rate (general)

    Memorise
    rate=changetime\text{rate} = \dfrac{\text{change}}{\text{time}}

    Statistics

    Mean

    Memorise
    mean=sum of valuesnumber of values\text{mean} = \dfrac{\text{sum of values}}{\text{number of values}}
    Combined Science revision notesOCR topic by topicOCR past papersPapers and mark schemesPractice questionsExam-style, with solutions

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